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2 Sheets-Sheet 1.

(Numoael.)

G. B.. PRATT. BLEVATOR No. 450,252. Patented Apr. 14, 1891.

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(No Model.) 2 Sheets-Sheet 2.

G. R. PRATT. ELEVATOR Patented Apr. 14, 1.891.

Mimosa/o Jv@ www Rohm/K N- my I VUNITED STATES i PATENT j OFFICE.

CHARLES R. PRATT, QF NEV YORK, N. Y.

ELEvAToR.

Y, SPEGIFICATION :forming part of Letters Patent No. 450,252, dated Aprill 14, 1891. A

Application led September 10, 1890. Serial No. 364,533. (No model.)

To all whom t may concern:

Be it known that I, CHARLES R. PRAT'L'a citizen of the United States, residing at New York, county and State of New York, have invented a certain new and useful Improvement in Elevators, of which the following is a specication.

My invention relates to elevators, and especially to that class known as screw elevators-that is, elevators in which a screw is turned by a suitable motor and a nut traveling on said screw moves a carriage or frame supporting suitable sheaves for the cable which supports the elevator.

The object of my present improvement is to economize in space required for the traveling carriage and other mechanism, to simplify the constructionof the carriage, to reduce friction and wear between the several parts, and to cheaply and efficiently steady or guide the carriage.

The invention consists in an improved carriage for said sheaves, in an improved arrangement of the sheaves, and in certain combinations hereinafter described and claimed.

In the accompanyingdrawings, which illus trate my invention, Figure l shows an end view of the carriage, the sheaves on one side of the carriage being in elevation and the sheaves on the other side of the carriage being in section. Fig. 2 is a side view of a section of the screw and track with the ca rriage and nut in place thereon, the sheaves being omitted on the side'of the carraige nearest to the observer. Fig. 3 is a section of the carriage-body on line X Xof Fig. 2.

The screw 1 is mounted in suitable bearings wherein it may turn, but which prevent longitudinal motion, and to this screw power is transmitted in any suitable way from an electric or other motor. Upon said screw is a nut 2, which is moved along by rotation of the screw, and which as it travels moves the carriage carrying the sheaves. Said carriage slides along a track or way, preferably consisting of a heavy plank 3, of about four inches in width, mounted on an iron beam 4. Above the carriage two planks 5 are placed, one on either side of a beam 6. To strengthen this guide in a transverse direction, a channel-iron or other shaped plate 7 is placed in the posi tion indicated in the drawings. Thebodyof the carriage preferably consists of a single steel forging 8', hav-ing on each side a projecting trunnion S, of sufficient length to receive the desired number of sheaves. To the lower side of said body is bolted or otherwise secured a projecting piece or guide 9, which is shaped to conform to the plank 3, and which is adapted to slide along the same. To the upper side of the body issecured a similar extension lO, which embraces the guide above described.

, Onto each trunnion S is slipped a chillediron or other sleeve 11, and Vover this sleeve rings 12, alternating with rows of steel balls 13, and over each row of balls a metal ring 14, the number of rings being the same as the number of sheaves to be employed. In the drawings five .such sheaves l5 are shown. When these have been putin place, the disk 16 is placed over the end of the trunnion and secured by means of suitable screws or other devices.

The rope or cable ordinarily employed in elevators of this character is about five-eighths of an inch in diameter. When I use ropes of this size,I make the sheaves one-eighth of an inch thicker, and place them on the trunnion side by side, so that they bear against each other through a portion at least of their surfaces, aud especially at the hub and at the rim. IVith this construction and .arrangei ment when the ropes are placed on the sheaves in the usualmanner there will be only one-eight inch distance between any two adjoining lengths of the rope. being of considerable diameter, would require lateral support were it not for the fact that by the arrangement described the several sheaves brace-and support each other. In the ,operation of this device the several sheaves will turn in the same direction,but at slightly* diierent speeds,as is well understood by those familiar with this character of devices. This being so, the friction between the contiguous surfaces of the sheaves will not be great. In view of the narrow bearing -surface which each sheave has ou the trunnion, there is'a strong tendency to wear the bearing-surface; but this is obviated by the arrangement of the frictionballs described.

. By comparing the present apparatus with that shown and described in Patent No.

The sheaves, e'

IOO

' nut thereon, a carriage consisting of a body 417,087, dated December 10, 1889, and that shown in my application', Serial No. 349,478, filed April 25, 1890, it Will be apparent that a verymatcrial savinghas been madein the fioorspace occupied by the apparatus, in the number of parts employed in making the same, as Well as a gain in general efficiency and durability of the apparatus, since the width of the carriage and track is reduced fully one-half and the cumbersome frame supporting the sheaves is dispensed with.

Itis evident-that the v guides and certain other parts of the construction may be varied in form Without departing from my invention.

Having thus described the invention, what I claim is 1. The combination,in an elevatorl1oisting apparatus,l of a traveling carriage having trunnions and several sheaves mounted thereon, the surfaces of saidy sheaves being in contact, a guide on the carriage between the trunnions, and a track directly under the carriage, substantially as described.

2. The combination of an elevator-screw, a

nut thereon and moved thereby, a carriage moved by said screw and nut, and several sheaves for the elevator1'ope mounted on trunnions on both sides of said carriage, the sheaves on each side being side by side and in contact with each other at or near their periphery, substantially as described.

3. The combination of an elevator-screw, a

ot metal with projecting trunnions, several narrower than the carriage and occupying the space between the sheaves, substantially as described. c 5. The combination, in an elevator apparatus, of a track or way, a carriage movable along said way, cable-sheaves supported by the carriage ou each side ofthe track, and a guide above the carriage for staying the same, substantially as described.

. 6. In an elevator-hoisting apparatus, the

combination of a carriage movable along a way or track and consisting of a body andprojecting trunnions, and cable-sheaves on said trunnions in surface contact with each other and separated from the trunnions by ball.

bearings` there being an independent row of vballs for each sheave, substantially as de* scribed. y

This specification signed and witnessed this 2d day ot' September, 1890 (JI-IAS. R. PRATT.

Witnesses:

CHARLES M. GATLIN, SEIBERT SCHUCK. 

